In communications installations and in communications terminal equipment connected thereto, required switching-oriented and operations-oriented functions are predominantly realized and coordinated by controllers of the communications installations. Required signalling information exchange and operating technology information exchange with the communications terminal equipment respectfully occurs via a signalling duplex channel with a message-oriented transmission procedure. The individual functions and suitable programs defining their interaction are stored in the program memories of the controllers. Variable information such as, for example, information about type, equipment features and performance features as well as terminal positions of the communications terminal equipment are inserted into the programs via parameters. The data belonging to the parameters are thereby separately stored for every communications terminal equipment in a region provided for this purpose in the data base usually established in a program-controlled communications installation. As a consequence of the central processing and administration and as a consequence of the parameter-controlled functions different functions can be allocated to a communications terminal equipment and can have modifications associated with the terminal equipment. The increasing demand for more user friendly and, thus, more complex performance features such as, for example, display of the telephone number of the calling communications terminal equipment at the called communications terminal equipment causes a considerable increase in the number of, in particular, switching functions and coordination functions in the communications installations and leads to a significant dynamic load on their controllers. Since the communications terminal equipment are being equipped with micro-processor systems or micro-computer systems to an increasing degree, some of the switching-oriented and operations-oriented functions are already realized in the communications terminal equipment.
It is also known that single systems or series systems, switching locations and operations-oriented consoles can be connected to a communications installation. Respectively different switching-oriented and operations-oriented functions are thereby allocated to the communications terminal equipment. In existing networks, these are rigidly allocated to every communications terminal equipment in the form of programs stored in their program memory and data appertaining thereto and representing the parameters that are stored in the data memory. A modification of this allocation is only possible with a physical change of program memory and/or the data appertaining thereto.